Injuries of the cervical spine represent one of the most physically disabling injuries compatible with survival. They cost the Society an estimated three quarters of a billion dollars per year in the USA. Although there have been a multitude of clinical studies, there are only a few studies that have been attempted to analyze the various surgical decompression and stabilization procedures that are used for the cervical spine trauma patient. The purpose of the present proposal is to study a realistic cervical spine injury model regarding changes in its stability due to several surgical decompression and stabilization procedures. Fresh cadaver cervical spine specimens will be utilized to model the clinically relevant hyperflexion injury. Surgical decompression procedures, e.g., laminectomy and facetectomy will also be modeled as well as several surgical stabilization procedures. The immediate stability of the spine models as well as their failure strengths will be determined. One of the most significant aspects of the experimental protocol is the determination of three-dimensional stability of the injury model after every injury and stabilization procedure utilizing the 3-D spinal motion measurement techniques pioneerd at the Yale Biomechanics Laboratory. The significance of the proposed study will be in several different areas. The results will provide a direct measurement of the relative loss of stability due to decompression procedure as well as a relative evaluation of the various surgical stabilization procedures. Additionally, 3-D physical understanding of the entire lower cervival spine will be determined providing a better understanding of the mechanics of normal, injured and surgically stabilized cervical spines.